I must have been one of the last homes to have ISDN - broadband was late coming to my village. Don't miss the expense, but broadband speeds round here are not that much faster.
We had L, a, b and later "b1" charge bands... charging was in "units" and each unit gave you a number of seconds, depending on charge band, and time of day/ day of week. Off peak wasfrom 18:00 to 08:00 and all weekend, while "peak" was split into two levels, lower was 08:00-09:00 and 13:00-18:00, with 09:00-13:00 being the even more stinging higher level.
I had to write software to determine costs of calls made via modems that offered 300/300, 600/600 and 1200/1200.